The Torah reading for Tisha B'Av morning began with the words, כי תוליד בנים that was taken from this week's Parsha. It is a warning from Moshe Rabbeinu not to get too "comfortable" in the land. During the reign of Yehoshua, the people all continued to observe the Torah. As the generations became "old" as the Torah uses the word, ונושנתם, it meant they were farther away in years from having witnessed the miracles of previous generations. This led to complacency and the tendency of crediting their successes to themselves and not to Hashem's kindness. It never bodes well when we take Hashem out of the equation. Moshe follows with the warning that if this takes place, you will be sent out of the land and be scattered among the nations. He further warns that you will remain few in numbers when you are forced to live among the nations. The bright spot of this rebuke is that if you truly seek out Hashem, even in places far away from Israel, Hashem will not forsake you. Teshuva will bring us back to the land and our former glory.